Bradycardia Algorithm

AHA 2015 ACLS Algorithm for the treatment of symptomatic bradycardia

Bradycardia in an adult is any heart rate less than 60 beats per minute (BPM), although symptoms may not manifest until the rate is less than 50. Bradycardia can be considered “normal” for a patient or asymptomatic such as highly trained athletes or while sleeping.

The primary bradycardic ECG rhythms you may see include: Sinus Bradycardia, First-degree AV block, Second-degree AV block, Type I —Wenckenbach/Mobitz I, Type II —Mobitz II, Third-degree AV block complete block.

A patient should be treated for bradycardia if they 1) present in a bradycardic heart rate 2) are symptomatic which may include a low BP, signs of poor perfusion, SOB, chest pain, altered mental status or are unstable and 3) symptoms are caused by the low rate.

Treatment of symptomatic bradycardia centers around speeding the rate up and/or reversing underlying causes.

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      Sinus Bradycardia

Sinus Bradycardia

1st Degree Heart Block

2nd Degree HB Type II (Mobitz II)

2nd Degree HB Type I (Wenckenbach/Mobitz I)

3rd Degree HB (Complete Heart Block)

Assess C-A-B

Maintain airway, Administer Oxygen and assist breathing as needed, Monitor Vitals, acquire 12-Lead ECG, Start IV/IO
Consider underlying causes of the bradycardia (H’s and T’s)
If the patient is stable, call for consult

If patient is symptomatic:

Administer Atropine 0.5 mg IV or IO bolus; Repeat the atropine every 3-5 minutes to a total dose of 3 mg.
(Do not delay TCP while starting IV or waiting for atropine to work in unstable patients)

If Ineffective:

Transcutaneous Pacing (verify capture and perfusion, use sedation as needed)
Catecholamine Infusion: Dopamine 2-10mcg/kg/min or Epinephrine 2-10mcg/min


  • Identifying and treating reversible causes of the bradycardia are essential in returning the patient to a better perfusing rhythm.
  • It is recommended you check for mechanical capture of TCP via the femoral pulse as muscular movement may mask or replicate a carotid pulse.
  • There are recommendations of increasing the milliamperes by 2mA over the amount in which you gained electrical capture.
  • Atropine may not work for transplanted hearts, Mobitz (Type II) or Third degree AV blocks.

Reversible Causes

Consider and treat potential reversible causes throughout an arrest or dysrhythmias 

Hypovolemia: S/S - Rapid heart rate and narrow QRS on ECG; other symptoms of low volume TX - Infusion of normal saline or Ringer’s lactate

Hypoxia: S/S -Slow heart rate TX - Airway management and effective oxygenation

Hydrogen Ion Excess (Acidosis): S/S - Low amplitude QRS on the ECGHyperventilation TX - consider sodium bicarbonate bolus

Hypoglycemia: S/S - Bedside glucose testing TX IV bolus of dextrose

HypokalemiaS/S - Flat T waves and appearance of a U wave on the ECG TX - IV Magnesium infusion

HyperkalemiaS/S - Peaked T waves and wide QRS complex TX - Consider calcium chloride, sodium bicarbonate, or an insulin and glucose protocol

Hypothermia: S/S - Typically preceded by exposure to a cold environment; TX - Gradual rewarming

Tension Pneumothorax: S/S -Slow heart rate and narrow QRS complexes on the ECG; difficulty breathing TX -Thoracostomy or needle decompression

Tamponade – CardiacS/S - Rapid heart rate and narrow QRS complexes on the ECG TX Pericardiocentesis

Toxins: S/S - Typically will be seen as a prolonged QT interval on the ECG; may see neurological symptoms TX Based on the specific toxin

Thrombosis (PE)S/S - Rapid heart rate with narrow QRS complexes on the ECG TX Surgical embolectomy or administration of fibrinolytics

Thrombosis (MI): S/S - ECG will be abnormal based on the location of the infarction TX Dependent on extent and age of MI

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